Thanks for the info. If parallels supports multithreaded applications I could likely just force it to run, or at least give an option to the user to 'force run' if they want to see if things will work anyway. I think I'll do that. It sounds like it's just the implementation of the windows API for checking how many logical cores a machine has is not reflecting the actual machine itself - but surely multithreaded programs are properly utilizing multiple cores on there (Parallels). Also, I suggest moving to v1.18a, otherwise the new big v1.20a update that's in the works will include a better simulation system, tool diagrams depicting the profile of the cutter specified via parameters, and a few other tidbits.
Thanks for checking out PixelCNC! ..and yes, please share your PixelCNC creations :)